How vain it is to sit down to write when you have not stood up to live.
– Henry David Thoreau
I shall live badly if I do not write, and I shall write badly if I do not live.
– Francoise Sagan
To write a good love letter, you ought to begin without knowing what you mean to say, and finish without knowing what you have written.
– Jean Jacques Rousseau
I especially like the last one.